Note: The HXT library does not work on the version of GHC I am using. The error is

benchmark: error: a C finalizer called back into Haskell.
use Foreign.Concurrent.newForeignPtr for Haskell finalizers.

I will re-run the benchmark when this is fixed.

I am one of the authors of hexpat, so this makes me biased: I do not know any switches to make the other libraries work at their best speed. So that you can check yourself, here is the software that does the benchmarks, including raw results for the graphs above: